P0430 again and again and again

[mb1500]

With 250K and everything running fine I bet your cat is going bad. The system is constantly running diagnostics and evaluating the perceived state of the catalyst, which is why the code can come off and on if the cat is still working but not 100%. The cat does not have to be clogged to be below threshold, could have zero affect on performance.

The proper fix is to replace the cat. If you don’t have inspections and aren’t worried about your catalyst performance or the EPA you can take a drilled out to 1/2” spark plug non-fouler and install it in between the rear O2 sensor and the pipe and you won’t get the code anymore.

 

[swathdiver]

Unless there is an air leak in the exhaust on that side, P0430 means what it says, a bad cat. It's not O2 sensors, they have their own codes.

 

[992dr]

With 250K and everything running fine I bet your cat is going bad. The system is constantly running diagnostics and evaluating the perceived state of the catalyst, which is why the code can come off and on if the cat is still working but not 100%. The cat does not have to be clogged to be below threshold, could have zero affect on performance.

The proper fix is to replace the cat. If you don’t have inspections and aren’t worried about your catalyst performance or the EPA you can take a drilled out to 1/2” spark plug non-fouler and install it in between the rear O2 sensor and the pipe and you won’t get the code anymore.

Unless there is an air leak in the exhaust on that side, P0430 means what it says, a bad cat. It's not O2 sensors, they have their own codes.

I appreciate the info fellas,
I have a couple of replacement cats that I was collecting for some future exhaust work. Looks like I'll be doing that sooner than later.

I'll be checking for leaks this morning

Thanks again

 

[992dr]

Just tested for leaks. Used the vacuum method like treehan suggested (thanks for the info). No leaks.

Here's a picture of the down stream and up stream O2 on the passenger side. They certainly look OE.
I think since I'll be replacing my cats I'll just replace the O2 sensors as well.

Question. Since I'll be replacing the cats will I have to have it retuned? I'd think no but, then again it will be a freer flowing cat compared to stock and slightly smaller in size.

I may swing by my mechanic to have him test the cats just to be sure. He's a good guy and will probably do it for nothing. I'll just weld something up for him in return haha.

Thanks again fellas, the info is much appreciated

 

[treehan77]

Dang sorry it wasn’t just an exhaust leak. I fixed a v8 Lexus with a tiny leak and p0430 that the dealer estimated the owner $2300 for new cats and sensors lol.

 

[992dr]

Dang sorry it wasn’t just an exhaust leak. I fixed a v8 Lexus with a tiny leak and p0430 that the dealer estimated the owner $2300 for new cats and sensors lol.

No worries my friend, been welding for 22+ years. This is fun stuff for me, plus I've been wanting to do this for a long time. Now, I'll have to get the show on the road. I'll end up driving my Charger while I do this, want it to be purty haha

 

[swathdiver]

No tune or relearn necessary, it will adjust quick enough. Just remember, new cats can throw a code within the first 50-100 miles as they break in. Perfectly normal, just clear it and keep driving.

Lots of folks say to change the O2 sensors at 100K miles. Mine were not lazy and let them go much much longer. What they did fail to do was calculate my alcohol percentage accurately.

 

[OR VietVet]

No tune or relearn necessary, it will adjust quick enough. Just remember, new cats can throw a code within the first 50-100 miles as they break in. Perfectly normal, just clear it and keep driving.

Lots of folks say to change the O2 sensors at 100K miles. Mine were not lazy and let them go much much longer. What they did fail to do was calculate my alcohol percentage accurately.

That alcohol thing has been an ongoing problem that GM engineers just can't seem to figure out....

 

[91RS]

It needs cats. And don’t get cheap aftermarket ones or you’ll be doing it again.

 

[992dr]

No tune or relearn necessary, it will adjust quick enough. Just remember, new cats can throw a code within the first 50-100 miles as they break in. Perfectly normal, just clear it and keep driving.

Lots of folks say to change the O2 sensors at 100K miles. Mine were not lazy and let them go much much longer. What they did fail to do was calculate my alcohol percentage accurately.

Ok cool, thanks for the heads up.
I'll probably replace them just because I'm at 250k miles and I put 100k on it without replacing them.
I love alcohol, I couldn't tell yah my percentage accurately it certainly fluctuates on a day to day. I can tell you it is high.

That alcohol thing has been an ongoing problem that GM engineers just can't seem to figure out....

Honestly have no idea what you guys are talking about

It needs cats. And don’t get cheap aftermarket ones or you’ll be doing it again.

I have had great luck with Maggy spun metallic cats, used them before with awesome results.
I do have two Magnaflow 59959 ss spun cats and two Kooks 307540 cats to choose from.

Thanks again guys, appreciate the info